1. Field of the Invention
This invention relates to the dispensation of fluids from a reservoir and particularly, but not exclusively, to the dispensation of ink in writing implements.
2. Description of Related Technology
There are a number of conventional techniques for delivering ink from an ink reservoir to the tip of a pen. The simplest technique is to rely on a gravity feed; however, this will not work well, and may not work at all, if the pen is turned upside down or if the ink is too viscous.
Another technique is to use a pressurised permanent gas, such as nitrogen, within the ink reservoir. The gas ensures that a sufficient pressure is maintained on the ink to push it towards the tip of the pen. However, there is a problem with this technique: as the ink is dispensed from the reservoir, the pressure in the reservoir drops, because there is a greater volume for the gas to occupy. In order to overcome this problem, the gas must be provided initially at high pressure, and must occupy a large part of the volume of the reservoir relative to the ink: in practice, up to 90% of the volume of the reservoir may initially be occupied by gas.